Energy harvesting and wave attenuation performance of a floating flexible annulus-shaped wave energy converter

Leveraging generalized elastic deformations of floating flexible structures for efficient wave energy harvesting and wave attenuation offers an innovative approach to marine energy development. This study proposes a novel multifunctional device, consisting of a floating flexible annular wave energy converter with an array of power take-off (PTO) units beneath it, capable of capturing incident wave energy while effectively attenuating waves in the interior water region. To investigate hydroelastic effects during energy harvesting and wave attenuation, a three-dimensional numerical wave tank (NWT) is developed, coupling the Finite Element Method (FEM) for structural modeling with Computational Fluid Dynamics (CFD) to simulate two-phase flow, enabling high-precision analysis. Fully bidirectional fluid–structure interaction is achieved through time-step interface mapping. After model validation, a comprehensive parametric study is performed. Results show that multi-modal elastic deformation leads to an increase of up to 87% in the overall capture width ratio, along with an approximately 30% improvement in interior quiescence, compared with its rigid counterpart. Concentrating PTO units on the seaside promotes early energy dissipation, enhancing wave attenuation. Additionally, moderate PTO coverage combined with a reduced geometric opening ratio broadens the effective bandwidth for energy capture while further stabilizing the interior water region. These findings highlight the potential of elastic floating structures for high-efficiency, multifunctional wave energy systems.